Coveted by the wealthiest members of the upper class, clergymen and royalty (Henry VIII and his first wife, Catherine of Aragon, had one), a boxwood carving was the ultimate symbol of luxury and status.

And then, in just a few decades, they disappeared. With no records of who made them, nor instructions detailing how they were made, an inimitable art was lost.

"They're objects that defy modern comprehension," says Alexandra Suda, a curator of European art at the Art Gallery of Ontario (AGO) in Toronto, Canada. "As small as they are, they represent the limitless potential for human creativity in a way that is universal."

Inside one half of the skull-shaped prayer bead, Christ enters carrying the cross while being flogged Credit: Photography by Craig Boyko

Suda is co-leading a five-year international study of the secrets behind these boxwood carvings.

A collaboration between scientists, conservators, curators and academics from some of the world's most prestigious institutions -- the Metropolitan Museum of Art, in New York, the Rijksmuseum, in Amsterdam, and NASA's Glenn Research Center, in Cleveland -- the study saw 30 of the 135 surviving carvings scanned and analyzed to figure out how they were made, and by whom.

A lost art

Even from a distance, the miniatures are baffling. Small enough to fit in your hand, their recessed religious scenes contain an astounding amount of detail. Look closely and you may see a crown of thorns on Christ's brow or a man's head looking out from the demonic mouth of hell.

Devotional objects by design, these beads, rosaries and altarpieces acted as tokens of faith and, like stained glass windows or religious sculptures, added an element of divine beauty to the act of prayer.

"They have this jigsaw puzzle, Rubik's cube, horror vacui kind of effect on you where you look at them," Suda says. "They're so intricate, and they're so stunningly carved that you almost immediately make that (religious) connection, in spite of the fact that you may not be a practicing Christian."

Thanks to a generous posthumous donation from the late publishing magnate Ken Thompson (the richest man in Canada when he died in 2006), the AGO has had the world's largest collection of boxwood miniatures since 2008, with 10 beads and two altarpieces in their collection.

This placed the museum in a unique position of leverage when, in 2011, Suda first proposed the idea of a large-scale investigation into the works' origins to former colleagues at the Metropolitan Museum of Art and later, Frits Scholten, senior curator of sculpture at the Rijksmuseum, who has written extensively on boxwood carvings.

The plan was to scan as many of the surviving boxwood miniatures as possible. Lisa Ellis, the AGO's sculpture and decorative arts conservator, took the lead, locating suitable facilities around the world in which to scan examples from the AGO, the Met and the Rijksmuseum, along with contributions from the Natural History Museum in London, the National Museum of Natural History in Paris, and the Cleveland Museum of Art, among other institutions.

Standing theories suggested that the works had been assembled in pieces, but the scans established the process definitively.

Once a piece of boxwood was shaped into a circle, it was bisected and then sliced into thin discs. Individual discs were then carved along the curve into single layers of the recessed final scene, and then stacked in such a way that the seams between the discs -- the points where they were connected -- were concealed from view.

A mystery maker

But while the secret of how the miniatures were constructed is a considerable discovery in itself, it has also upended the dominant theory about who created them.

There are no known records of specific creators (the pieces are, surprisingly, unsigned), but it was largely accepted that the miniatures were produced by between four and six different workshops in Flanders. With estimates that each must have taken about four to five years to make, this seemed the most logical explanation.

A close-up view of the opened St. James the Greater prayer bead Credit: Courtesy Art Gallery of Ontario

However, the consistency in construction that the scans revealed seem to suggest a single master craftsman.

"That was the thing that really hit us over the head like a frying pan: This is the product of one guy's vision -- probably with a few apprentices and assistants -- who was extraordinarily gifted. When he died, this practice ceased to exist," Suda says.

"I rarely use the term genius, but I would say that this person if not a genius, is certainly an exception to the norm."

As of now, there are few leads as to who this mystery maker might have been, but Suda is now determined to discover their identity and source of inspiration.

"I'm dying to know where they got all of the imagery. When you start to think yeah, this is amazing that they were able to make these physically, the next logical question is, 'How did they come up will all of these incredibly imaginative images?'" Suda says.

"The thing that really connected with me was that whoever this artist was was certainly inviting their original viewer to consider the possibility of it all, and he was quite successful because we're still thinking about that today."